A 10\ μ W Front-End Enabling 200 ps Resolution in High-Efficiency Large Area Monolithic Pixel Sensors

This paper presents a low-power, low-mismatch in-pivel circuit optimized for large area monolithic pixel sensors. The design addresses key challenges by achieving low power consumption <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(12.5\ μ W/channel)</tex> high detection efficiency with a low Equivalent Noise Charge <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(200\ e⁻)</tex> , and low time jitter (200 ps). An optimized power grid minimizes performance variation across the chip area and mitigates noise injection from dynamic voltage drops. The pixel-to-pixel charge threshold mismatch of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">200\ rms\ e⁻</tex> can be further reduced by a factor of 4 through a local 3-bit (DAC) for pixel-level threshold tuning. The circuit is implemented in a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2.3\ cm × 3.0\ cm</tex> monolithic pixel sensor, integrating a matrix of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">132× 192</tex> hexagonal pixels ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">150\ μ m²</tex> area). It is produced in a 130 nm SiGe BiCMOS process featuring SiGe Heterojunction Bipolar Transistors (HBTs). This sensor is designed for the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</tex> scanner, enabling high-resolution molecular imaging. It offers significant potential for applications requiring high-efficiency detection in large-scale systems.